1. Field of the Invention
The present invention relates to a light guide plate, and a backlight assembly and a liquid crystal display having the same, and more particularly, to a light guide plate including prism patterns normal to a path of incident light, and a backlight assembly and a liquid crystal display having the light guide plate.
2. Description of Related Art
Generally, a liquid crystal display (LCD) is a device for displaying an image using liquid crystal having optical and electrical characteristics, such as anisotropic refractive index and anisotropic dielectric constant. The LCD is typically thinner and lighter than other display devices such as a cathode ray tube (CRT) and a plasma display panel (PDP) while having a lower operation voltage and lower power consumption. Thus, the LCD has been widely used.
The LCD includes an LCD panel, which has a thin film transistor (TFT) substrate, a color filter substrate opposite to the TFT substrate, and a liquid crystal layer interposed between the TFT and color filter substrates. The liquid crystal layer is used to change light transmittance through the LCD panel. A backlight assembly is typically used together with the LCD panel to provide light to the LCD panel.
A backlight assembly typically includes a lamp for generating light, and a light guide plate (LGP) for guiding a path of light from the lamp disposed along a side surface of the backlight assembly, toward the LCD panel. Light guide plates may be classified as flat or wedge types. The flat type light guide plate includes a light-incident portion on which light is incident and a light-facing portion which is opposite the light-incident portion having the same thickness. The wedge type light guide plate tapers from a light-incident portion to a light-facing portion.
To prevent the light guide plate from being discolored and improve a brightness characteristic, a prism light guide plate in which a prism pattern is formed on a bottom surface thereof has been developed. In the case of the flat type light guide plate whose thickness is constant, the light guided into the light guide plate substantially satisfies a total reflection condition, so that only the prism pattern may cause the light to exit to the outside.
However, in case of the wedge type light guide plate, when light is guided into the light guide plate, the light does not satisfy the total reflection condition and exits laterally, thereby causing a light loss. The light loss increases from the light-incident portion to the light-facing portion.
Specifically, if point light sources are used, the light emitted from the respective point light sources and reflected by the prism pattern may appear as white spots or white lines depending on its recognition angle. As a result, such white spots or lines may deteriorate the visibility.